Recently it has become desirable to construct a high intensity linear accelerator for producing a 100 mA continuous duty deuteron beam to a flowing liquid lithium target. Machines of this type are needed as neutron factories for the testing and development of metals to be applied to the first wall in future fusion energy power generating stations. They are also useful in a branch of the fusion energy program known as inertial confinement which requires heavy ion accelerators. Because the beam will render a drift tube linac radioactive, it should be structured so that alignment and maintenance will not require manned entry into the tanks. The accelerator will provide unprecedented continuous duty power and beam intensity and should have a functional life of at least about 20 years. A 100 mA deuteron beam will be fired at either 20 or 35 MeV into a rapidly flowing lithium target that must be exposed directly to the beam without the aid of an isolation window.
Previous accelerators have either operated at a low duty factor by pulsing the beam or they operated at continuous duty with a low intensity beam. In all cases the net loss of beam was low enough to allow maintenance of the machine to be carried out by hands on methods. In certain circular machines, the beam extraction devices could not be well protected from beam losses and achieved a level of activity that finally rendered the machines dangerous from a maintenance standpoint.
A deuteron beam, by virtue of the bound neutron, is a highly activating beam. Such machines in the past have been forced to operate at low duty to prevent activation of the accelerator's structure. Solution of the hands on maintenance and alignment problem is an important step to raising the duty factor of deuteron accelerators.